Digi 90031300 Manual Do Utilizador
Appendix E
95
Four-Wire Direct Wiring
Four-Wire Direct wiring connects T1 Modem Bank units where longer synchronous cable runs are necessary. While
not as fast as Eight-Wire connections (the maximum data transfer rate is 1.8 megabaud
not as fast as Eight-Wire connections (the maximum data transfer rate is 1.8 megabaud
1
), this wiring method is more
economical, and is sufficient in all but the most demanding high-performance applications. This means that terminal
users should see no degradation in performance. In the Four-Wire Direct wiring mode, the clock signals are encoded
with the receive and transmit data signals, so only two twisted pairs are required. The Four-Wire Direct cable is a
twisted pair cable with a male HD-15 (high-density DB-15) connector at one end and a female HD-15 at the other
end. The cable should be shielded, and the shield must be connected to the HD-15 connector shell at both ends. See
Figure 34.
users should see no degradation in performance. In the Four-Wire Direct wiring mode, the clock signals are encoded
with the receive and transmit data signals, so only two twisted pairs are required. The Four-Wire Direct cable is a
twisted pair cable with a male HD-15 (high-density DB-15) connector at one end and a female HD-15 at the other
end. The cable should be shielded, and the shield must be connected to the HD-15 connector shell at both ends. See
Figure 34.
Figure 34
Four-Wire Direct Daisy Chain Cable Wiring
1
If each T1 line transmits at 1.544 Mbit/second, only one T1 Modem Bank can be connected to this line and still maintain the full data rate. See
Table 8 on page 96 for restrictions on cable lengths.